Double Barrels and Piston Valve Question

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Postby An Apple Pie » Tue Nov 28, 2006 4:43 pm

Okay I am building a semi-auto golf ball cannon. I plan on using a 2" piston valve. I was going to have double barrels connected with unions to 90* Bends that are connected to a tee that is then attached to the valve via another union. I am using the unions so that I could detach the tee from the valve and screw one of the barrels on, so it could be double or single barreled.

My question is how much distance would I loose with the double barrels over the single? I would just build it and test it, but I do not want to make an extra loading mechanism, mag, barrel, and I would have saved two unions.

My guess is that it would go about 2/3 as far, but I really have no clue.
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Postby c0mpl3x » Tue Nov 28, 2006 5:12 pm

<blockquote id="quote"><font size="1" face="tahoma,verdana,arial" id="quote">quote:<hr height="1" noshade id="quote">Originally posted by An Apple Pie
[br]Okay I am building a semi-auto golf ball cannon. I plan on using a 2" piston valve. I was going to have double barrels connected with unions to 90* Bends that are connected to a tee that is then attached to the valve via another union. I am using the unions so that I could detach the tee from the valve and screw one of the barrels on, so it could be double or single barreled.

My question is how much distance would I loose with the double barrels over the single? I would just build it and test it, but I do not want to make an extra loading mechanism, mag, barrel, and I would have saved two unions.

My guess is that it would go about 2/3 as far, but I really have no clue.

<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

with 2 barrels at .8:1, or 2:1, it's going to double for one single barrel
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Postby An Apple Pie » Tue Nov 28, 2006 5:15 pm

Okay so it will cut the distance in half. If that is not what you were saying then I am lost.

-Edit-
Wait can a homemade piston valve actuate when there is air flowing through the pilot, to fill it.
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Postby TalonXxX » Tue Nov 28, 2006 9:38 pm

most likely not... only if your pilot was considerably larger than your fill. You probably need a ball valve on a tee with a your inlet on the ball valve and your out on the bottom of the tee. Even if your pilot was larger... it still might not perform as well.
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Postby An Apple Pie » Tue Nov 28, 2006 10:18 pm

Wait, Talon are you saying to put the inlet on a ball valve, and to shut it off before I shoot. If so that would defeat the purpose of it being semi-auto. It would have a QD for an inlet(whatever size that hole is) and a 1/4" High Flow Blow Gun Valve from McMaster. Would that work on a piston valve, and if not would it work on a QEV
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Postby Velocity » Tue Nov 28, 2006 10:30 pm

I usually advocate barrel-sealing valves... but this might be a good opportunity to use a chamber sealing valve. A barrel-sealing valve would have 3 90* turns (the way I see it; may be other ways) while a chamber sealing valve only has 2 90* turns.

Here is my <a href="http://www.spudfiles.com/uploader/uploadFiles/chambersealingidea.JPG">idea</a>. You can add unions where necessary.

As for your other question, get a three-way ball valve (or solenoid valve, if you want to get fancy). Hook up one of the ports to your compressor, one to the atmosphere, and one to the pilot. When the ball valve is turned one way, the atmosphere port is closed off, allowing air to enter the valve. When the ball valve is turned the other way, the compressor port is closed off, allowing air to exit the valve
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Postby An Apple Pie » Tue Nov 28, 2006 10:35 pm

Rmich interesting idea with the chamber sealing valve. I would do this except for the fact that I do not have a lathe at the moment.

I know how a three way ball valve works but I am wondering if there is a way to make it truley semi-auto and still use a barrel sealing piston valve, and use a blow gun or similar trigger type firing mechanism. Oh and my budget for the whole thing is $150-$200 so I can not use any psycho stuff that costs a lot.
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Postby Velocity » Tue Nov 28, 2006 10:59 pm

I believe <a href="http://cgi.ebay.com/Asco-Solenoid-Valve-3-Wa-24VDC-1-4-Air-Water-Lt-Oil-NIB_W0QQitemZ330055550109QQihZ014QQcategoryZ87087QQrdZ1QQcmdZViewItem">this</a> should suit your purposes (someone correct me if I am wrong). It is a three-way valve, 24 VDC. This will involve electronics in your semi-auto. To use this, buy a 3/4" QEV off of mcmaster, and use this to pilot that, which will in turn pilot the piston valve.
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Postby An Apple Pie » Tue Nov 28, 2006 11:03 pm

Wait so does this valve do the same thing a a 3 way ball valve except electronic? If so could I use oh say a light switch to actuate it. I am not much of an electronic guy(mainly a mechanical guy) so pardon me for my posible stupidity on the subject. Also what batteries etc. would I need for it(I assume 9vs, bot how many because 9 doesn't go into 24 evenly)?
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Postby Velocity » Tue Nov 28, 2006 11:51 pm

I believe it does do the same thing as a 3-way ball valve; like you, I am not much of an electronic guy. Hooking up 3 9V batteries should be sufficient to actuate it. And yes, a regular light switch would work for it (its the same thing as a solenoid sprinkler valve; however, I would not try to modify it pneumatically).

And I cannot believe that I didn't think of this before, but it is a simple solution to your semi-auto problem which I used myself on my golf ball semi-auto: filling from the chamber. Here is what you do:

1) connect your air compressor to the chamber, through a male QD fitting; you can use a ball valve to regulate it if you like; not necessary though
2) Add a light spring to your piston, which will help it seal for chamber filling
3) Use a QEV for the pilot valve, and pilot that with a blowgun

This simplifies everything... check out my tiger semi-auto; it uses the same principle
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